Implement ADR-0024 Phase A: SIP-level TP launcher MVP

Scope (Phase A):
- D1: world_size fallback = SIP count (rank = SIP, TP boundary)
- D9: greenlet-local get_rank + _bind_rank (single-driver fallback = 0)
- D10: torch.ahbm.set_device + torch.accelerator.set_device_index alias
- D11: tensor placement scoped to current-device SIP (post-hoc pe_index
  shift — ADR-0026 replaces with structural coords)
- D12/D13: multi-greenlet run() with simple round-robin scheduler;
  hybrid dispatch (ws == SIP count → multi-greenlet, else legacy
  single-worker for ccl.yaml override compat)
- D7 partial: backend.all_reduce submit + yield + wait via launch()'s
  new _defer_wait flag; parent-less greenlets skip yield
- Relaxed shard-count check (len(shards) > 0 instead of == world_size)
- rank_to_pe = SIP-representative [(r, 0, 0)] when ws <= n_sips

Deferred to Phase B:
- Engine-routed install (D2) — keeps sideband
- install_plan.py module (D6) — keeps install.py
- Epoch barrier (D7 full) — simple yield is sufficient for ring ws=2 mock
- Validator registry (D8)
- Cross-SIP multi-greenlet + real kernel integration — matrix
  ring_default_ws hangs in SimPy drain despite ADR-0025 direction fix;
  marked xfail(run=False) pending Phase B diagnosis (suspected per-rank
  kernel_args / program_id mismatch)

Tests:
- test_ccl_ddp_launcher.py (6 new tests) — D1/D9/D10/D11/D12/D13
- test_ccl_allreduce_matrix.py — ring_default_ws xfail'd, override
  cases (ring_tcm_8 / hbm_8 / sram_8 / multi_cube / mesh_2x2 /
  tree_binary_7) all pass via legacy path

514 tests pass, 1 xfail.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -29,3 +29,4 @@ build/
 
 # Logs
 *.log
+.claude/